Analytical Chemistry I – PAC 1101- PCA 1101 PDF

Analytical Chemistry I – PAC 1101- PCA 1101 Dr. Adel Lashien – Dr. Rehab Magdy NUB Faculty of Pharmacy Room No. : 4106 Dr. A. Lashien - Dr. Rehab Magdy...

Analytical Chemistry I – PAC 1101- PCA 1101 Dr. Adel Lashien – Dr. Rehab Magdy NUB Faculty of Pharmacy Room No. : 4106 Dr. A. Lashien - Dr. Rehab Magdy 1  Analytical Chemistry I – PAC 1101- PCA 1101 Text Books 1. Chemistry Authors: Steven S. Zumdahl, Susan A. Zumdahl University of lllinois Eighth Edition , ISBN-13: 978-0-495-82992-8 ISBN-10: 0-495-82992-7 2. Vogel’s Quantitative Inorganic Analysis Author: G. Svehla Department of Chemistry University College – Cork - Ireland Sixth Edition , ISBN 0-582-21866-7 Dr. A. Lashien - Dr. Rehab Magdy 2  Analytical Chemistry I – PAC 1101- PCA 1101 Chapter 3 Reactions and identification of Anions Dr. A. Lashien - Dr. Rehab Magdy 3  Analytical Chemistry I – PAC 1101- PCA 1101 Lecture 8 Qualitative Analysis Of Carbon Containing Anions Dr. A. Lashien - Dr. Rehab Magdy 4  Analytical Chemistry I – PAC 1101- PCA 1101 Objectives 1. Draw a flow diagram to classify oxides. 2. Classify anions to their two main classes. 3. Explain the scientific principle of the classification of anions. 4. Give examples of the anions of the classes: IA, IIA, IB and IIB. 5. What is the dry test and what is the wet test? 6. Name the carbon containing anions. 7. Explain the separation and identification of the carbon containing anions using a flow chart. Dr. A. Lashien - Dr. Rehab Magdy 5  Analytical Chemistry I – PAC 1101- PCA 1101 Introduction The elements, non-metals appear in the upper-right corner of the periodic table (to the right of the heavy zigzag line which separates them from the metals). Chemically, non-metals tend to gain electrons in reactions with metals and form monoatomic negative ions, or anions. For example, Cl-, O2-, S2-, P3- … etc. Such anions are monatomic. However, non-metals can combine together or with some metals and form polyatomic anions. Examples include, OH-, NO3-, SO42-, Cr2O72-...etc. Through out this chapter you will study the chemical behavior of the common anions and the chemical methods we use to identify each anion in a sample of an unknown composition. Dr. A. Lashien - Dr. Rehab Magdy 6  Analytical Chemistry I – PAC 1101- PCA 1101 Dr. A. Lashien - Dr. Rehab Magdy 7  Analytical Chemistry I – PAC 1101- PCA 1101 Scheme of Classification - The methods available for the detection of anions are not as systematic as those for cations. - No satisfactory scheme has yet been proposed which permits the separation of the common anions into major groups, and the subsequent separation of each group into its constituents. - However, the following scheme of classification has been found to work well in practice although some of the anions belong to more than one subdivision. - The scheme divides anions into two classes: I. Class A, and II. Class B. Dr. A. Lashien - Dr. Rehab Magdy 8  Analytical Chemistry I – PAC 1101- PCA 1101 Dr. A. Lashien - Dr. Rehab Magdy 9  Analytical Chemistry I – PAC 1101- PCA 1101 Table 1: Common Class A-Anions Dr. A. Lashien - Dr. Rehab Magdy 10  Analytical Chemistry I – PAC 1101- PCA 1101 Table 2: Common Class B-Anions Dr. A. Lashien - Dr. Rehab Magdy 11  Analytical Chemistry I – PAC 1101- PCA 1101 1- Carbon Containing Anions Carbonate and bicarbonate, CO32-, HCO3- Anions - The parent acid of both is carbonic acid, H2CO3. - Carbonic acid (dibasic acid) is a very weak acid that exists only in solutions. - On heating carbonic acid, carbon dioxide gas evolves. H2CO3 (aq) → H2O (l) + CO2 (g) - Both carbonates (except for group I carbonates) and bicarbonates decompose on heating producing CO2 gas. MCO3 (s) → MO (s) + CO2 (g) 2HCO3- (s) → CO32-(s) + H2O (l) + CO2 (g) Dr. A. Lashien - Dr. Rehab Magdy 12  Analytical Chemistry I – PAC 1101- PCA 1101 Reactions of Carbonates and Bicarbonates Dr. A. Lashien - Dr. Rehab Magdy 13  Analytical Chemistry I – PAC 1101- PCA 1101 Dr. A. Lashien - Dr. Rehab Magdy 14  Analytical Chemistry I – PAC 1101- PCA 1101 Dr. A. Lashien - Dr. Rehab Magdy 15  Analytical Chemistry I – PAC 1101- PCA 1101 Analysis of Mixtures Mixture of CO32- and HCO3- Principle of Separation - Both anions have similar reactions, but solutions of carbonates form precipitates immediately on cold upon the addition of an aqueous solutions of AgNO3, CaCl2 or BaCl2 or any metal chloride (except of group I) while bicarbonates do not. Dr. A. Lashien - Dr. Rehab Magdy 16  Analytical Chemistry I – PAC 1101- PCA 1101 Dr. A. Lashien - Dr. Rehab Magdy 17  Analytical Chemistry I – PAC 1101- PCA 1101 Solve all of just testing questions and work sheets 22 and 23 Dr. A. Lashien - Dr. Rehab Magdy 18